Abstract
The static magnetization and dynamic susceptibility responses of the cluster system within a Griffiths phase of the magnetocaloric compound () have been investigated. A novel cluster-glass state within the Griffiths phase is formed at a characteristic freezing temperature where short-range ferromagnetic correlations set in the paramagnetic regime. Ferromagneticlike correlations are built up at around 155 K, which suddenly become frozen at a lower temperature , thus in analogy with a reentrant spin glass behavior. The ac susceptibility near the freezing temperature follows a critical slowing down process characterized by and dynamic exponents and , similar to well-known spin glass systems. The nonlinear ac susceptibility analysis shows clearly the existence of a transition associated to the reentrant behavior. The origin of the intermediate cluster-glass phase inside the Griffiths phase is proposed to be the result of a combination of short-ranged RKKY intralayer positive exchange interactions between rare-earth ions and antiferromagnetic exchange between adjacent interlayers involving Si and Ge atoms in connection to the atoms.
2 More- Received 7 November 2018
- Revised 13 January 2019
DOI:https://doi.org/10.1103/PhysRevB.99.054419
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